1. Field of the Invention
The subject invention generally pertains to loading docks, and more specifically to a shield system for shielding an area below a dock leveler.
2. Description of Related Art
A typical loading dock of a building includes an exterior doorway with an elevated platform for loading and unloading vehicles, such as trucks and trailers. To compensate for height differences between the loading dock platform and an adjacent bed of a truck or trailer, many loading docks have a dock leveler. A typical dock leveler includes a deck, also known as a ramp or dockboard, which is pivotally hinged along its back edge to vary the height of its front edge. An extension plate, or lip, extends outward from the deck""s front edge to span the gap between the rear of the truck bed and the front edge of the deck. The lip is usually moveable between a stored position to an extended, operative position. In the extended, operative position, the lip extends from the deck""s front edge and rests upon the truck bed to form a bridge between the two. This allows personnel and material handling equipment to readily move on and off the vehicle during loading and unloading operations.
To help shield against weather while a vehicle is being serviced at the dock, usually some type of seal is installed around the perimeter of the doorway. Such seals are usually installed along the upper and side edges of the doorway to help seal any air gaps that may otherwise exist between the face of the building and the rear of the vehicle. The dock leveler lip resting upon the rear of the vehicle is often relied upon to seal most of the doorway""s lower edge.
However, the area or pit underneath a dock leveler""s ramp is usually exposed to outside air. This can create problems, especially when there is a significant temperature differential between the indoor and outdoor air. For example, warm outside air may condense underneath a relatively cool ramp of a dock leveler used in a cold storage warehouse. The condensation can promote corrosion of various parts of the dock leveler. Conversely, a heated building during the winter may loose a significant amount of heat by thermal conduction through the ramp, as cold outside air cools the ramp from underneath. Thus, regardless of whether the outside air is colder or warmer than the inside air, it may be beneficial to shield the underside of a dock leveler from outside air, as proposed in U.S. Pat. No. 4,682,382.
The ""382 patent suggests using a rectangular panel to help shield the area underneath a dock leveler. A lower edge of the panel is coupled to the dock, while the panel""s upper edge has a resilient sealing strip for sealing against the rear of a vehicle. The effectiveness of that seal, however, may depend on how squarely a vehicle backs into the dock and may further depend on the shape or contour of the vehicle""s rear surface. Moreover, in the absence of a vehicle, it appears that the dock leveler lip, rather than the rectangular panel, is relied upon to shield the underside of the ramp from the outside air. Also, to move the lip from a stored, pendant position to an extended, operative position, the ramp apparently must lift the lip up and over the upper edge of the panel before the lip can be set back down atop the truck bed. As the lip travels over the top of the sealing strip, the underside of the ramp may be momentarily exposed to an inrush of outside air.
To help shield a pit area below a dock leveler, a shield system includes a shield having a lower edge adjacent the pit area and an upper edge coupled to the ramp. The upper edge moves with the ramp, while the lower edge remains below the dock. Thus, the shield provides a weather-shielding span whose vertical length varies with movement of the ramp.
In some embodiments, the vertical length of the weather-shielding span varies by virtue of a roller about which the shield is wrapped.
In some embodiments, the upper edge of the shield can be coupled to the ramp by being attached to a dock leveler""s lip extension.
In some embodiments, the upper edge of the shield can be coupled to the ramp by being attached directly to the ramp.
In some embodiments, the upper edge of the shield can be coupled to the ramp by being attached to a hinge that connects the lip extension to the ramp.
In some embodiments, the shield includes notched out areas to accommodate various loading dock related items such as a vehicle restraint or lip keepers.
In some embodiments, the shield includes a compliant seal capable of sealing against the rear of a vehicle.
In some embodiments, a shield includes several loops of fabric to create a seal that is compliant without the drawbacks of foam. Foam generally has relatively low wear resistance and tends to absorb moisture and hold dirt.